Crystals cause microbes to produce more methane

A CRYSTALLINE form of a synthetic red dye has been found to help methane-producing microbes – which occur naturally in coal seams and food waste – produce up to ten times more methane.

Researchers from University of New South Wales (UNSW), Australia discovered that needle-like crystals of the synthetic phenazine dye known as “neutral red” – normally used for staining cells under a microscope – are capable of harvesting electrons from decomposing organic and inorganic matter.

The team discovered the crystals when the neutral red was added to a mixture of coal and groundwater microbes in the absence of oxygen.

Mike Manefield, associate professor at UNSW said, “The crystals act as electron sponges, harvesting electrons from minerals and bacteria in the mixture and then transferring them with a lot of power to the methane-producing microbes, boosting their growth.”

The crystal technologies have been tested in a field environment in coal boreholes. Small quantities of neutral red were injected 80 m underground at three sites into the water-saturated coal seam and a five- to tenfold increase in methane production was observed during a 12-month period.

Manefield said, “Our research has shown that the crystals can lead to a massive leap in methane production – a tenfold increase from coal, and an 18-fold increase from food waste.

“We also expect our approach will work with renewable feedstocks for methane-producing microbes, such as woody plant material and the by-products of municipal wastewater treatment.”

Coal seam gas wells typically have a short lifespan and depleted ones cause surface damage in the form of litter. Enhancing the natural methane production could reduce the need to build new seams, and a longer lifespan for existing wells.

The increased biogas harvested from the microbes will also help reduce greenhouse gas emissions from burning other fossil fuels to meet demand.

Energy & Environmental Science, DOI: 10.1039/C5EE03085D